Mixing apparatus



April 26, 1949. G. G. BRUCK v MIXING APPARATUS Filed March 7, 1946 m/ltA rol? GEORGE G. 5506 Patented Apr. 26, 1949 MIXING APPARATUS George G.Bruck, East Orange, N. J., assignor to Raytheon Manufacturing Company,Newton, Mass, a corporation of Delaware Application March '7, 1946,Serial No. 652,628

18 Claims.

This invention relates to mixing apparatus, and more particularly tomixing apparatus for combining periodic waves, especially, but notnecessarily, electromagnetic waves having different frequencies in themicrowave region of the spectrum, to produce a resultant wave whosefrequency is an arithmetic function, for example, the sum of ordifference between the frequencies of the initial waves.

While not limited thereto, the present invention is admirably adaptedfor use in a communication system, such as is disclosed in the copendingapplication of George G. Bruck, Philip E. Volz, Paul J. Pontecorvo andMalcolm C. Vosburgh, entitled Radio communication system,

' Serial No. 650,716, filed February 27, 1946, for

heterodyning microwave carriers to produce a beat-frequency wave.

One of the objects of the present invention is to provide mixingapparatus of the general character'indicated in which impedance-matchingproblems, normally difilcult of solution, are

means, for examp1e,'a double T-shaped waveguide assembly including across-arm common to both T's and a pair of branch arms perpendicular tosaid cross-arm and to each other, for dividing a pair of periodic wavesapplied thereto into two oppositely-phased pairs of similarly-phasedconstituent waves, and two additional pairs of constituent waves, thewaves of one of said additional pairs being of like phase and the wavesof the otheradditional pair being of opposite phase. The constituentwaves of each of said firstnamed pairs, and the constituent waves ofeach of said second-named pairs are combined in means,

' for example, a pair of oppositely-disposed, seriesconnected,non-linear impedances terminating the outer ends of the above referredto waveguide cross-arm, to derive therefrom, respectively, two resultantwaves of like phase and two resultant waves of opposite phase. All ofsaid resultant waves are combined in means, for example, an inductiveimpedance connected in parallel with the above referred to non-linearimpedances, whereby said first-named resultant waves cancel each otherto produce a zero output,

[ while said second-named resultant waves add to each other to produce afinal output whose fre- .quency is an arithmetic function of thefrequencies of the initial waves.

In the accompanying specification there shall be described, and in theannexed drawing shown, an illustrative embodiment of the mixingapparatus of the present invention. It is, however, to beclearly'understood that the present invention is not to be limited tothe details herein shown and described for purposes of illustrationonly, inasmuch as changes therein may be made without the exercise ofinvention, and within the true spirit and scope of the claims heretoappended.

In said drawing, the single figure is a schematic diagram of amixingdevice assembled in accord-- ance with the principles of the presentinvention.

Referring now more in detail to the aforesaid illustrativeembodiment ofthe present invention, with particular reference to the drawingillustratin'gthe same, the numeral l0 generally designates what may betermed a double T-shaped wave-guide assembly. Such an assembly includesa cross-arm II from the center of which, or from what will hereinafterbe called a common junction l2, extends two branch arms I3 and I 4, saidcross-arm being common to both T's, and said branch arms beingperpendicular to said crossarm, and to each other. As herein shown, the

' branch arm ll recedes from the observer for a short distance from thecommon junction l2,

then bends downwardly, and is then" twisted through an angle of i Theopposite ends of the cross-arm terminate, respectively, in non-linearimpedances, for example, rectifying crystals l5 and I6, said crystalsbeing oppositely disposed with respect to each other, and connected inseries through a resistor I1 and a source l8 of direct current. Theconductors connecting said crystals pass through insulators l9 to 22,inclusive mounted in the crossarm II, the insulators l9 and 2| being ofsuch construction (not specifically shown) as to present capacitances 23and 24 between one side of each of said crystals and the cross-armitself, the latter being grounded as shown. The crystals 15v and I6 arefurther connected to provide parallel outputs to ground through acapacitor 25 and the primary winding 26 of an output transformer 21having a secondary winding 28.

The source l8 of direct current constitutes a bias for the purpose ofenabling operation of the crystals at favorable points alongtheircharacteristic curves, and the series circuit is for the purpose ofpassing equal currents through said crystals to assure their similarbehavior even though both be mismatched to the wave guide assembly.

For an understanding of the operation of the device, assume that twoinput waves of different frequencies uh and w'h are both traveling downthe branch arm I3 toward the common junction I! with their electricvectors pointing in the same direction, arbitrarily, to the right. Asthese waves reach the junction l2, each splits into two constituentwaves, the waves traveling along the cross-arm ll toward the crystal I5having their electric vectors pointing in the same direction, namely,downwardly; and the waves traveling along said cross-arm toward thecrystal l6 having their electric vectors, likewise, pointing in the samedirection, namely, upwardly. Thus, there arrives at the crystal I 5, twosimilarly-phased constituent waves, and there arrives at the crystall6,two also similarly-phased constituent waves, although it is to benoted that the two pairs of waves are oppositely phased. At the crystali5, resultant waves, whose frequencies correspond to the sum of anddifference between the frequencies of the initial waves, and whosephases may be considered positive because' there component waves are inphase, are produced; and at the crystallG, additional resultant waves,having the same frequencies as said first-named resultant waves, andhaving phases which may also be considered positive because theircomponent waves are also in phase,

are produced. However, as to each other, the resultant waves obtained,respectively, at the two crystals are 180 out of phase, and set up equalvoltages of opposite polarities across said crystals. Inasmuch asparallel outputs are taken from these crystals, cancellation occurs andno output appears across the primary winding 25 of the transformer 21.

Now assume that the input to the branch I3 includes at least one of thewaves wn, '11, and further assume that the other of these waves, havingits electric vector pointing, for example, upwardly at the junction I2,is applied to the branch arm l4. As before, the wave 011 or w'htraveling along the branch arm l3 will split at the junction l2, thewave traveling along the cross-arm ll toward the crystal i having itselectric vector pointing downwardly, and the wave traveling along saidcross-arm toward the crystal l6 having its electric vector pointingupwardly. When the wave traveling ,along the branch arm I4 reaches thejunction 12, it; too, splits into two waves, one traveling along thecross-arm H toward the crystal l5 and one traveling along said cross-armtoward the crystal IS, with both having their electric vectors pointingin the same direction, namely, upwardly. Thus, there arrives at thecrystal l5, two constituent waves which are out of phase, and therearrives at the crystal l6 two constituent waves which are in phase.Therefore, there are produced at the crystal l5, two resultant waveswhose frequencies corresponds to the sum of and difference between thefrequencies of the initial waves, and whose phases may be considerednegative because their component waves are out of phase; while at thecrystal Hi, there are produced two resultant waves having the samefrequencies as said first-named resultant waves, and having phases whichmay be considered positive because their component waves are in phase.

As to each other, the resultant ,waves obtained, respectively, at thetwo crystals are in phase, and set up equal voltages of like polaritiesacross said crystals. Inasmuch as parallel outputs are taken from thesecrystals, addition occurs, and constant-amplitude, sum and differenceoutput waves appear across the primary winding 26 of the transformer 21.Either of these waves may be finally selected by appropriately tuningthe output circuit.

This. completes the description of the aforesaid illustrative embodimentof the present invention. Objects and advantages thereof, in addition tothose set forth in earlier portions of this specification, will readilyoccur to those skilled in the art to which the same relates.

What is claimed is:

1. Apparatus for mixing periodic waves having different frequenciescomprising: a double T- shaped wave-guide assembly, having a cross-armcommon to both Ts and a pair of branch arms perpendicular to saidcross-arm and to each other, receptive of said waves, for deriving fromone,

' two constituent waves of opposite phase, and

from another, two constituent waves of like phase; and means, receptiveof all of said constituent waves, for deriving therefrom an output wavewhose frequency is an arithmetic function of the frequencies of theinitial waves.

2. Apparatus for mixing periodic waves having different frequenciescomprising: means, receptive of said waves, for deriving from one, twoconstituent waves of opposite phase, and from another, two constituentwaves of like phase; and means, including a pair of series-connected,nonlinear impedances and an inductive impedance in parallel therewith,receptive of all of said constituent waves, for deriving therefrom anoutput wave whose frequency is an arithmetic function of the frequenciesof the initial waves.

3. Apparatus for mixing periodic waves having different frequenciescomprising: 'a double T- shaped wave-guide assembly, having a cross-armcommon to both Ts and a pair of branch arms perpendicular to saidcross-arm and to each other, receptive of said waves, for deriving fromone, two constituent waves of opposite phase, and from another, twoconstituent waves of like phase; and means, including a pair ofseries-connected, nonlinear impedances and an inductive impedance inparallel therewith, receptive of all of said constituent waves, forderiving therefrom an output wave whose frequency is an arithmeticfunction of the frequencies of the initial waves.

4. Apparatus for mixing periodic waves having different frequenciescomprising: a double T- shaped wave-guide assembly, having a cross-armcommon to both T's and a pair of branch arms perpendicular to saidcross-arm and to each other, receptive of said waves, for deriving fromone,

' ing said resultant waves to derive therefrom an output wave whosefrequency is an arithmetic function of the frequencies of the initialwaves.

5. Apparatus for mixing periodic waves having different frequenciescomprising: a double T- shaped wave-guide assembly, having a cross-armcommon to both Ts and a pair of branch arms perpendicular to saidcross-arm and to each other, receptive of said waves, for deriving fromone, two constituent waves of opposite phase, and from another, twoconstituent waves of like phase; a pair of oppositely-disposed,series-connected, non-linear impedances terminating said cross-arm forcombining said first-named constituent waves, respectively, with saidsecondnamed constituent waves to derive therefrom two resultant waves ofopposite phase; and means for combining said resultant waves to derivetherefrom an output wave whose frequency is an arithmetic function ofthe frequencies of the initial waves.

6. Apparatus for mixing periodic waves having different frequenciescomprising: a double T- shaped wave-guide assembly, having a cross-armcommon to both Ts and a pair of branch arms perpendicular-to saidcross-arm and to each other, receptive of said waves, for deriving fromone, two constituent waves of opposite phase, and from another, twoconstituent waves of like phase; a pair of oppositely-disposed,series-connected, non-linear impedances terminating said cross-arm forcombining said first-named constituent waves, respectively, with saidsecondnamed constituent waves to derive therefrom two resultant waves ofopposite phase; and an inductive impedance connected in parallel withsaid non-linear impedances for combining said resultant waves to derivetherefrom an output wave whose frequency is an arithmetic function ofthe frequencies of the initial waves.

7. Apparatusfor mixing periodic waves having different frequenciescomprising: means, receptive of said waves, for dividing the same intotwo oppositely-phased pairs of similarly-phased constituent waves, andtwo additional pairs of constituent waves, the waves of one of saidadditional pairs being of like phase and the waves of the otheradditional pair being of opposite phase; means for combining theconstituent waves of each of said first-named pairs to derive therefromtwo resultant waves of like phase, and for combining the constituentwaves of each of said second-named pairs to derive therefrom tworesultant waves of opposite phase; and means for so combining saidfirst-named resultant waves as to produce a zero output, and for socombining said second-named resultant waves as to produce an output wavewhose frequency is an arithmetic function of the frequencies of theinitial waves.

8. Apparatus for mixing periodic waves having different frequenciescom-prising: a double T- shaped wave-guide assembly, having a cross-armcommon to both Ts and a pair of branch arms perpendicular to saidcross-arm and to each other, receptive of said waves, for dividing thesame into two oppositely-phased pairs of similarly-phased constituentwaves, and two additional pairs of constituent waves, the waves of oneof said additional pairs being of like phase and the waves of the otheradditional pair being of opposite phase; means for combining theconstituent waves of each of said first-named pairs to derive therefromtwo resultant waves of like phase, and for combining the constituentwaves of each of said second-named pairs to derive therefrom tworesultant waves of opposite phase;

and means for so combining said first-named resultant waves as toProduce a zero output, and

for so combining said second-named resultant different frequenciescomprising: a double 1- shaped wave-guide assembly, having a cross-armcommon to both Ts and a pair of branch arms perpendicular to saidcross-arm and to each other, receptive Of said waves, for dividing thesame into two oppositely-phased pairs of similarly-phased constituentwaves, and two additional pairs of constituent waves, the waves of oneof said additional pairs being of like phase and the waves of the otheradditional pair being of opposite phase; a pair of oppositely-disposed,series-connected, non-linear impedances terminating said cross-arm forcombining the constituent waves of each of said first-named pairs toderive therefrom two resultant waves of like phase, and for combiningthe constituent waves of each of said second-named pairs to derivetherefrom two resultant waves of opposite phase;

and means for so combining said first-named resultant waves as toproduce a zero output, and for so combining said second-named resultantwaves as to produce an output wave whose frequency is an arithmeticfunction of the frequencies of the initial waves.

10. Apparatus for mixing periodic waves having difierent frequenciescomprising: a double T-shaped wave-guide assembly, having a crossarmcommon to both Ts and a pair of branch arms perpendicular to saidcross-arm and to each other, receptive of said waves, for dividing thesame into two oppositely-phased pairs of similarly-phased constituentwaves, and two additional pairs of constituent waves, the waves of oneof said additional pairs being of like phase and the waves of the otheradditional pair being of opposite phase; a pair of oppositely-disposed,series-connected, non-linear impedances terminating said cross-arm forcombining the constituentwaves of each of said first-named pairs toderive therefrom two resultant waves of like phase, and for combiningthe constituent waves of each of said second-named pairs to derivetherefrom two resultant waves of opposite phase; and an inductiveimpedance connected in parallel with said non-linear impedances for socombining said first-named resultant waves as to produce a zero output,and for so combining said second-named resultant waves as to produce anoutput wave whose frequency is an arithmetic function of the frequenciesof the initial waves. 1

11. A wave-guide assembly comprising: a main wave-guide section having anon-linear impedance at each of the opposite ends thereof; and a pair ofbranch wave-guide sections, perpendicular to said main Wave-guidesection and to each other, extending outwardly from said main wave-guidesection.

12. A wave-guide assembly comprising: a main wave-guide section having a-non-linear impedance at each of the opposite ends thereof; one side ofeach of said impedances being capacitively coupled to said mainwave-guide section; and a pair of branch wave-guide sections,perpendicular to said main wave-guide section and to each other,extending outwardly from said main wave-guide section.

13. A wave-guide assembly comprising: a main wave-guide section having acrystal detector at each of the opposite ends thereof; and a pair ofbranch wave-guide sections, perpendicular to said main wave-guidesection and to each other, extending outwardly from said wave-guidesection.

14. A wave-guide assembly comprising: a main wave-guide section having acrystal detector at each of the opposite ends thereof; one side of eachof said crystal detectors being capacitively coupled to said mainwave-guide section; and a pair of branch wave-guide sections,perpendicular to said main wave-guide section and to each other,extending outwardly from said main wave-guide section.

15. A wave-guide assembly comprising: a main wave-guide section having apair of oppositelydisposed, series-connected, non-linear impedances atthe opposite ends thereof; and a pair of branch wave-guide sections,perpendicular to said main wave-guide section and to each other,

the opposite ends thereof; and a pair of branch wave-guide sections,perpendicular to said main wave-guide section and to each other,extending outwardly from said main wave-guide section.

18. A wave-guide assembly comprising: a main wave-guide section having apair of oppositelydisposed, series-connected, crystal detectors at theopposite ends thereof; one side of each of said crystal detectors beingcapacitively coupled to said main wave-guide section, and a pair ofbranch wave-guide sections, perpendicular to said main wave-guidesection and to each other, extending outwardly from said main wave-guidesection.

GEORGE G. BRUCK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,413,939 Benware Jan. 7, 194'!FOREIGN PATENTS Number Country Date 116,110 Australia Nov. 4, 1942

